Devices and methods for wavefront sensing and corneal topography

ABSTRACT

Devices and methods for wavefront sensing and keratometry are described. A device includes a lens assembly, a wavefront sensor, and a keratometer. The wavefront sensor includes: the lens assembly; a first light source configured to emit first light and transfer the first light emitted from the first light source toward an eye through the lens assembly; an array of lenses that is distinct from the lens assembly; and a first image sensor configured to receive light, from the eye, transmitted through the lens assembly and the array of lenses. The keratomer includes: the lens assembly; a second light source that is distinct from the first light source and configured to emit second light and transfer the second light emitted from the second light source toward the eye; and a second image sensor configured to receive light, from the eye, transmitted through the lens assembly.

RELATED APPLICATION

This application claims priority to, and benefit of, U.S. ProvisionalPatent Application Ser. No. 62/210,893, filed Aug. 27, 2015, entitled“Devices and Methods for Wavefront Sensing and Corneal Topography,”which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

This application relates generally to wavefront sensing and cornealtopography, and more particularly, portable devices that are capable ofperforming both wavefront sensing and corneal topography.

BACKGROUND

Eyes are important organs, which play a critical role in human's visualperception. An eye has a roughly spherical shape and includes multipleelements, such as cornea, lens, vitreous humour, and retina.Imperfections in these components can cause reduction or loss of vision.For example, too much or too little optical power in the eye can lead toblurring of the vision (e.g., near-sightedness and far-sightedness), andastigmatism can also cause blurring of the vision. Because the cornea isresponsible for a significant portion of the eye's optical power, it isalso important to accurately measure its topography. In addition,corneal topography provides important information for laser refractivesurgery.

Both wavefront sensors and corneal topographers are important tools inophthalmology. Wavefront sensors provide information indicating one ormore aberrations in the eye. In particular, wavefront sensors have anadvantage over auto-refractors in that wavefront sensors can measurehigher order aberrations. Various corneal topographers (e.g., Placidotopographers) are used for measuring the shape of cornea. An earlyintervention of visual impairment through an early diagnosis may allowreversal, or control over further progression of, such visualimpairment. It is believed that almost 80% of visual impairment casesare preventable with proper diagnosis and intervention.

However, diagnostic instruments that can perform both wavefront sensingand corneal topography are not readily available, partly due to theirsizes and costs. Especially, many children do not receive the eye carethey need, and they are at the greatest risk of undetected visionproblem. A portable device that can perform both wavefront sensing andcorneal topography is expected to allow wider and more frequentscreening for visual impairments, which will prevent a great number ofvisual impairment cases.

SUMMARY

Accordingly, there is a need for portable devices that can perform bothwavefront sensing and corneal topography. Such devices and relatedmethods optionally complement or replace conventional devices andmethods. Such devices provide portability, performance, and conveniencethat are not available from conventional devices and methods.

The above deficiencies and other problems associated with conventionaldevices and corresponding methods are reduced or eliminated by thedisclosed devices.

As described in more detail below, some embodiments involve a portabledevice that includes a lens assembly, a wavefront sensor, and akeratomer. The wavefront sensor includes: the lens assembly; a firstlight source configured to emit first light and transfer the first lightemitted from the first light source toward an eye through the lensassembly; an array of lenses that is distinct from the lens assembly;and a first image sensor configured to receive light, from the eye,transmitted through the lens assembly and the array of lenses. Thekeratomer includes: the lens assembly; a second light source that isdistinct from the first light source and configured to emit second lightand transfer the second light emitted from the second light sourcetoward the eye; and a second image sensor configured to receive light,from the eye, transmitted through the lens assembly.

In some embodiments, the second light source is configured to transferthe second light emitted from the second light source toward the eyewithout transmitting the second light emitted from the second lightsource through the lens assembly.

In some embodiments, the second light source is configured to project anarray of spots on the eye.

In some embodiments, the second light source includes a diffuser with aspot array pattern and one or more light emitters placed behind thediffuser and configured to emit light toward the diffuser.

In some embodiments, the second light source includes a diffuser with aspot array pattern and one or more light emitters and one or morereflectors arranged to send light toward the diffuser from behind thediffuser.

In some embodiments, the second light source includes a diffuser with aspot array pattern and a plurality of light emitters placed along aperiphery of the diffuser. At least a first portion of the diffuser istransparent and at least a second portion of the diffuser is configuredto diffuse light.

In some embodiments, the lens assembly includes a lens that is tiltedfrom an optical axis of the device.

In some embodiments, the first light source is configured to transferthe first light emitted from the first light source off an optical axisof the device.

In some embodiments, the first image sensor is configured to receive thelight from the eye while the first light source emits the first light.

In some embodiments, the second image sensor is configured to receivethe light from the eye while the second light source emits the secondlight.

In some embodiments, the lens assembly is a doublet lens.

In some embodiments, the lens assembly includes two or more separatelenses.

In some embodiments, the device includes a beam steerer configured totransfer light from the eye, transmitted through the lens assembly,toward the first image sensor and/or the second image sensor.

In some embodiments, the beam steerer is a beam splitter.

In some embodiments, the device includes an eyecup configured toposition the eye relative to the device.

In accordance with some embodiments, a portable device includes awavefront sensor and a keratometer. The wavefront sensor includes afirst light source configured to emit first light and transfer the firstlight emitted from the first light source toward an eye through the lensassembly; an array of lenses; and a first image sensor configured toreceive light, from the eye, transmitted through the lens assembly andthe array of lenses. The keratomer includes a second light source thatis distinct from the first light source and configured to emit secondlight and transfer the second light emitted from the second light sourcetoward the eye. The second light source is configured to project anarray of spots on the eye. The keratometer also includes a second imagesensor configured to receive light, from the eye, transmitted throughthe lens assembly.

In accordance with some embodiments, a method includes transferringfirst light emitted from a first light source toward the eye through alens assembly; and, in response to transferring the first light emittedfrom the first light source toward the eye through a lens assembly:transferring light from the eye through the lens assembly and an arrayof lenses; and receiving the light from the eye, transferred through thelens assembly and the array of lenses, at a first image sensor. Themethod also includes transferring second light emitted from a secondlight source toward the eye; and, in response to transferring the secondlight emitted from the second light source toward the eye: transferringlight from the eye through the lens assembly; and receiving the lightfrom the eye, transferred through the lens assembly, at a second imagesensor. The method further includes analyzing the light received at thefirst image sensor and determining one or more aberrations associatedwith the eye; providing information that indicates the one or moreaberrations associated with the eye; analyzing the light received at thesecond image sensor and determining a curvature of a cornea of the eye;and providing information that indicates the curvature of the cornea ofthe eye.

In accordance with some embodiments, an electronic device includes oneor more processors; and memory storing one or more programs. The one ormore programs include instructions for initiating a first light sourceto emit first light. The first light emitted from the first light sourceis transferred toward an eye through a lens assembly. The one or moreprograms also include instructions for, while the first light sourceemits the first light, receiving, at a first image sensor, a first imageof light from the eye, transferred through the lens assembly and anarray of lenses; initiating a second light source to emit second light.The second light emitted from the second light source is transferredtoward the eye. The one or more programs further include instructionsfor, while the second light source emits the second light, receiving, ata second image sensor, a second image of light from the eye, transferredthrough the lens assembly.

In accordance with some embodiments, a method is performed at anelectronic device that includes one or more processors and memorystoring instructions for execution by the one or more processors. Themethod includes initiating a first light source to emit first light. Thefirst light emitted from the first light source is transferred toward aneye through a lens assembly. The method also includes, while the firstlight source emits the first light, receiving, at a first image sensor,a first image of light from the eye, transferred through the lensassembly and an array of lenses; initiating a second light source toemit second light. The second light emitted from the second light sourceis transferred toward the eye. The method further includes, while thesecond light source emits the second light, receiving, at a second imagesensor, a second image of light from the eye, transferred through thelens assembly.

In accordance with some embodiments, a computer readable storage mediumstores one or more programs for execution by one or more processors ofan electronic device. The one or more programs include instructions,which, when executed by the one or more processors of the electronicdevice, cause the device to initiate a first light source to emit firstlight. The first light emitted from the first light source istransferred toward an eye through a lens assembly. The one or moreprograms also include instructions, which, when executed by the one ormore processors of the electronic device, cause the device to, while thefirst light source emits the first light, receive, at a first imagesensor, a first image of light from the eye, transferred through thelens assembly and an array of lenses; initiate a second light source toemit second light. The second light emitted from the second light sourceis transferred toward the eye. The one or more programs further includeinstructions, which, when executed by the one or more processors of theelectronic device, cause the device to, while the second light sourceemits the second light, receive, at a second image sensor, a secondimage of light from the eye, transferred through the lens assembly.

Thus, portable devices that include both wavefront sensors and cornealtopographers are provided with faster, more efficient methods forperforming wavefront sensing and corneal topography, thereby increasingthe effectiveness, efficiency, portability, and user satisfaction withsuch devices. Such devices and corresponding methods may complement orreplace conventional methods for performing wavefront sensing andcorneal topography.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the various described embodiments,reference should be made to the Description of Embodiments below, inconjunction with the following drawings in which like reference numeralsrefer to corresponding parts throughout the figures.

FIG. 1A illustrates optical components of a portable device inaccordance with some embodiments.

FIG. 1B illustrates wavefront sensing with the portable device shown inFIG. 1A, in accordance with some embodiments.

FIG. 1C illustrates corneal topography with the portable device shown inFIG. 1A, in accordance with some embodiments.

FIGS. 1D-1G illustrate light sources configured to project an array ofspots in accordance with some embodiments.

FIG. 1H illustrates a portable device in accordance with someembodiments.

FIG. 2 is a block diagram illustrating electronic components of aportable device in accordance with some embodiments.

FIG. 3 is a block diagram illustrating a distributed computing system inaccordance with some embodiments.

FIG. 4 is a flowchart representing a method of optical measurements witha portable device, in accordance with some embodiments.

FIG. 5 is a flowchart representing a method of optical measurements witha portable device, in accordance with some embodiments.

FIG. 6 illustrates exemplary calibration curves for adjusting one ormore aberrations of an eye based on a position of the eye relative tothe device, in accordance with some embodiments.

FIG. 7 is an exemplary image of an eye with projection of a spot arraypattern in accordance with some embodiments.

DESCRIPTION OF EMBODIMENTS

Conventional wavefront sensors are widely used for detecting one or moreaberrations of an eye. Conventional corneal topographers are used fordetermining a profile of a cornea. However, conventional devices thatcan perform both wavefront sensing and corneal topography have not beenmade portable. It is not simply the size of the conventional devicesthat has prevented miniaturization of such devices. Rather, theinventors of this application have observed that the conventionaldevices, if just reduced in size, would suffer from significant errors.The inventors of this application have discovered that the errors aremainly due to the positioning of the eye relative to the pupil plane ofa device. Conventional devices include a bulky mechanism for aligningthe position of an eye so that the eye is positioned on the pupil plane.However, such a bulky mechanism cannot be used in portable devices, andwithout the alignment mechanism, significant errors were observed inminiaturized devices. The inventors of this application have discoveredthat a new optical design, which includes a lens assembly in aparticular position, significantly reduces the impact of the positioningerror. Portable devices with such lens assemblies can perform bothwavefront sensing and corneal topography with superior performancecompared to conventional devices.

Reference will be made to embodiments, examples of which are illustratedin the accompanying drawings. In the following description, numerousspecific details are set forth in order to provide a thoroughunderstanding of the various described embodiments. However, it will beapparent to one of ordinary skill in the art that the various describedembodiments may be practiced without these particular details. In otherinstances, methods, procedures, components, circuits, and networks thatare well-known to those of ordinary skill in the art are not describedin detail so as not to unnecessarily obscure aspects of the embodiments.

It will also be understood that, although the terms first, second, etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first image sensor could betermed a second image sensor, and, similarly, a second image sensorcould be termed a first image sensor, without departing from the scopeof the various described embodiments. The first image sensor and thesecond image sensor are both image sensors, but they are not the sameimage sensor.

The terminology used in the description of the embodiments herein is forthe purpose of describing particular embodiments only and is notintended to be limiting of the invention. As used in the description ofthe invention and the appended claims, the singular forms “a,” “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will also be understood that theterm “and/or” as used herein refers to and encompasses any and allpossible combinations of one or more of the associated listed items. Itwill be further understood that the terms “comprises” and/or“comprising,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

As used herein, the term “if” may be construed to mean “when” or “upon”or “in response to determining” or “in response to detecting,” dependingon the context. Similarly, the phrase “if it is determined” or “if [astated condition or event] is detected” may be construed to mean “upondetermining” or “in response to determining” or “upon detecting (thestated condition or event)” or “in response to detecting (the statedcondition or event),” depending on the context.

FIG. 1A illustrates optical components of portable device 100 inaccordance with some embodiments.

Device 100 includes lens assembly 110. In some embodiments, lensassembly 110 is a doublet lens, as shown in FIG. 1A. For example, adoublet lens is selected to reduce spherical aberration and otheraberrations (e.g., coma and/or chromatic aberration). In someembodiments, lens assembly 110 is a triplet lens. In some embodiments,lens assembly 110 is a singlet lens. In some embodiments, lens assembly110 includes two or more separate lenses. In some embodiments, lensassembly 110 includes an aspheric lens. In some embodiments, a workingdistance of lens assembly 110 is between 10-100 mm (e.g., between 10-90mm, 10-80 mm, 10-70 mm, 10-60 mm, 10-50 mm, 15-90 mm, 15-80 mm, 15-70mm, 15-60 mm, 15-50 mm, 20-90 mm, 20-80 mm, 20-70 mm, 20-60 mm, 20-50mm, 25-90 mm, 25-80 mm, 25-70 mm, 25-60 mm, or 25-50 mm). In someembodiments, an effective focal length of a first lens (e.g., the lenspositioned closest to the pupil plane) is between 10-150 mm (e.g.,between 10-140 mm, 10-130 mm, 10-120 mm, 10-110 mm, 10-100 mm, 10-90 mm,10-80 mm, 10-70 mm, 10-60 mm, 10-50 mm, 15-150 mm, 15-130 mm, 15-120 mm,15-110 mm, 15-100 mm, 15-90 mm, 15-80 mm, 15-70 mm, 15-60 mm, 15-50 mm,20-150 mm, 20-130 mm, 20-120 mm, 20-110 mm, 20-100 mm, 20-90 mm, 20-80mm, 20-70 mm, 20-60 mm, 20-50 mm, 25-150 mm, 25-130 mm, 25-120 mm,25-110 mm, 25-100 mm, 25-90 mm, 25-80 mm, 25-70 mm, 25-60 mm, 25-50 mm,30-150 mm, 30-130 mm, 30-120 mm, 30-110 mm, 30-100 mm, 30-90 mm, 30-80mm, 30-70 mm, 30-60 mm, 30-50 mm, 35-150 mm, 35-130 mm, 35-120 mm,35-110 mm, 35-100 mm, 35-90 mm, 35-80 mm, 35-70 mm, 35-60 mm, 35-50 mm,40-150 mm, 40-130 mm, 40-120 mm, 40-110 mm, 40-100 mm, 40-90 mm, 40-80mm, 40-70 mm, 40-60 mm, 40-50 mm, 45-150 mm, 45-130 mm, 45-120 mm,45-110 mm, 45-100 mm, 45-90 mm, 45-80 mm, 45-70 mm, 45-60 mm, 45-50 mm,50-150 mm, 50-130 mm, 50-120 mm, 50-110 mm, 50-100 mm, 50-90 mm, 50-80mm, 50-70 mm, or 50-60 mm). In some embodiments, for an 8 mm pupildiameter, the lens diameter is 16-24 mm. In some embodiments, for a 7 mmpupil diameter, the lens diameter is 12-20 mm. In some embodiments, thef-number of lens assembly is between 2 and 5. The use of a common lensassembly (e.g., lens assembly 110) in both a wavefront sensor and acorneal topographer allows the integration of the wavefront sensor andthe corneal topographer without needing large diameter optics.

Device 100 also includes a wavefront sensor. In some embodiments, thewavefront sensor includes lens assembly 110, first light source 120, anarray of lenses 132 (also called herein lenslets), and first imagesensor 140. In some embodiments, the wavefront sensor includesadditional components.

First light source 120 is configured to emit first light and transferthe first light emitted from the first light source toward eye 170through lens assembly 110, as depicted in FIG. 1B.

Although FIGS. 1A-1C include eye 170 and its components (e.g., cornea172 and lens 174) to illustrate the operations of device 100 with eye170, eye 170 and its components are not part of device 100.

Turning back to FIG. 1A, in some embodiments, first light source 120 isconfigured to emit light of a single wavelength or a narrow band ofwavelengths. Exemplary first light source 120 includes a laser (e.g., alaser diode) or a light-emitting diode (LED).

In some embodiments, first light source 120 includes a lens (as shown inFIG. 1A) to change the divergence of the light emitted from first lightsource 120 so that the light, after passing through lens assembly 110,is collimated.

In some embodiments, first light source 120 includes a pinhole (e.g.,having a diameter of 1 mm or less, such as 400 μm, 500 μm, 600 μm, 700μm, 800 μm, 900 μm, and 1 mm).

Because lens assembly 110 is positioned closer to eye 170 than firstlight source 120 (e.g., light from first light source 120 passes throughlens assembly 110), in some cases, it is important to reduce backreflection of the light at lens assembly. Thus, in some embodiments, ananti-reflection coating is applied on a back surface (and optionally, afront surface) of lens assembly 110 to reduce back reflection. In someembodiments, first light source 120 is configured to transfer the firstlight emitted from first light source 120 off an optical axis of device100 (e.g., an optical axis of lens assembly 110), as shown in FIG. 1B(e.g., the first light emitted from first light source 120 propagatesparallel to, and offset from, the optical axis of lens assembly 110).This reduces back reflection of the first light emitted from first lightsource 120, by lens assembly 110, toward first image sensor 140. In someembodiments, the wavefront sensor includes a quarter-wave plate toreduce back reflection, of the first light, from lens assembly 110(e.g., light reflected from lens assembly 110 is attenuated by thequarter-wave plate). In some embodiments, lens assembly 110 includes alens that is tilted from an optical axis of the device, to reduce backreflection, of the first light, from the tilted lens (e.g., byreflecting the light toward a direction that does not face first imagesensor 140). In some embodiments, a curvature of a lens in lens assembly110 is selected so that reflection, of the first light, from the lens isdirected toward a direction that does not face first image sensor 140.

First image sensor 140 is configured to receive light, from eye 170,transmitted through lens assembly 110 and the array of lenses 132. Insome embodiments, the light from eye 170 includes light scattered at aretina or fovea of eye 170 (in response to the first light from firstlight source 120). For example, as shown in FIG. 1B, light from eye 170passes multiple optical elements, such as lens assembly 110, beamsteerer 122, lens 124, beam steerer 126, mirror 128, and lens 130, andreaches first image sensor 140.

Beam steerer 122 is configured to reflect light from light source 120and transmit light from eye 170, as shown in FIG. 1B. Alternatively,beam steerer 122 is configured to transmit light from light source 120and reflect light from eye 170. In some embodiments, beam steerer 122 isa beam splitter (e.g., 50:50 beam splitter, polarizing beam splitter,etc.). In some embodiments, beam steerer 122 is a wedge prism, and whenfirst light source 120 is configured to have a linear polarization, thepolarization of the light emitted from first light source 120 isconfigured to reflect at least partly by the wedge prism. Light of apolarization that is perpendicular to the linear polarization of thelight emitted from first light source 120 is transmitted through thewedge prism. In some cases, the wedge prism also reduces light reflectedfrom cornea 172 of eye 170.

In some embodiments, beam steerer 122 is tilted at such an angle (e.g.,an angle between the optical axis of device 100 and a surface normal ofbeam steerer 122 is at an angle less than 45°, such as 30°) so that thespace occupied by beam steerer 122 is reduced.

In some embodiments, device 100 includes lenses 124 and 130 to modify aworking distance of device 100.

The array of lenses 132 is arranged to focus incoming light ontomultiple spots, which are imaged by first image sensor 140. As inShack-Hartmann wavefront sensor, an aberration in a wavefront causesdisplacements (or disappearances) of the spots on first image sensor140. In some embodiments, a Hartmann array is used instead of the arrayof lenses 132. A Hartmann array is a plate with an array of apertures(e.g., through-holes) defined therein.

In some embodiments, lens 124, lens 130, and the array of lenses 132 arearranged such that the wavefront sensor is configured to measure areduced range of optical power. A wavefront sensor that is capable ofmeasuring a wide range of optical power may have less accuracy than awavefront sensor that is capable of measuring a narrow range of opticalpower. Thus, when a high accuracy in wavefront sensor measurements isdesired, the wavefront sensor can be designed to cover a narrow range ofoptical power. For example, a wavefront sensor for diagnosing low andmedium myopia can be configured with a narrow range of optical powerbetween 0 and −6.0 diopters, with its range centering around −3.0diopters. Although such a wavefront sensor may not provide accuratemeasurements for diagnosing hyperopia (or determining a prescription forhyperopia), the wavefront sensor would provide more accuratemeasurements for diagnosing myopia (or determining a prescription formyopia) than a wavefront sensor that can cover both hyperopia and myopia(e.g., from −6.0 to +6.0 diopters). In addition, there are certainpopulations in which it is preferable to maintain a center of the rangeat a non-zero value. For example, in some Asian populations, the opticalpower may range from +6.0 to −14.0 diopters (with the center of therange at −4.0 diopters), whereas in some Caucasian populations, theoptical power may range from +8.0 to −12.0 diopters (with the center ofthe range at −2.0 diopters). The center of the range can be shifted bymoving the lenses (e.g., lens 124, lens 130, and/or the array of lenses132). For example, defocusing light from eye 170 can shift the center ofthe range.

Device 100 further includes a corneal topographer. In some embodiments,the corneal topographer includes lens assembly 110, second light source150, and second image sensor 160. In some embodiments, as shown in FIG.1A, second image sensor 160 is distinct from first image sensor 140. Insome embodiments, the wavefront sensor includes additional components.

Second light source 150 is configured to emit second light and transferthe second light emitted from second light source 150 toward eye 170. Asshown in FIG. 1C, in some embodiments, second light source 150 isconfigured to transfer the second light emitted from second light source150 toward eye 170 without transmitting the second light emitted fromsecond light source 150 through lens assembly 110 (e.g., second lightfrom second light source 150 is directly transferred to eye 170 withoutpassing through lens assembly 110).

In some embodiments, device 100 includes beam steerer 126 configured totransfer light from eye 170, transmitted through lens assembly 110,toward first image sensor 140 and/or second image sensor 160. Forexample, when device 100 is configured for wavefront sensing (e.g., whenlight from first light source 120 is transferred toward eye 170), beamsteerer 126 transmits light from eye 170 toward first image sensor 140,and when device 100 is configured for corneal topography (e.g., whenlight from second light source 150 is transferred toward eye 170), beamsteerer 126 transmits light from eye 170 toward second image sensor 160.

Second light source 150 is distinct from first light source 120. In someembodiments, first light source 120 and second light source 150 emitlight of different wavelengths (e.g., first light source 120 emits lightof 900 nm wavelength, and second light source 150 emits light of 800 nmwavelength; alternatively, first light source 120 emits light of 850 nmwavelength, and second light source 150 emits light of 950 nmwavelength). In some embodiments, beam steerer 126 is a dichroic mirror(e.g., a mirror that is configured to transmit the first light fromfirst light source 120 and reflect the second light from second lightsource 150, or alternatively, reflect the first light from first lightsource 120 and transmit the second light from second light source 150).In some embodiments, beam steerer 126 is a movable mirror (e.g., amirror that can flip or rotate to steer light toward first image sensor140 and second image sensor 160). In some embodiments, beam steerer 126is a beam splitter. In some embodiments, beam steerer 126 is configuredto transmit light of a first polarization and reflect light of a secondpolarization that is distinct from (e.g., perpendicular to) the firstpolarization. In some embodiments, beam steerer 126 is configured toreflect light of the first polarization and transmit light of the secondpolarization.

In some embodiments, second light source 150 is configured to project anarray of spots on the eye. In some embodiments, the array of spots isarranged in a grid pattern (e.g., FIG. 7). In some embodiments, secondlight source 150 is configured to project light in a pattern of aplurality of concentric rings (e.g., Placido's disk).

In some embodiments, second light source 150 includes one or more lightemitters 152 (e.g., light-emitting diodes) and diffuser 154 (e.g., adiffuser plate having an array of spots). Exemplary embodiments ofsecond light source 150, which are configured to project an array ofspots in accordance with some embodiments, are described below withrespect to FIGS. 1D-1G.

FIG. 1D illustrates a front view (shown on the left-hand side of FIG.1D) and a side view (shown on the right-hand side of FIG. 1D) of secondlight source 150 in accordance with some embodiments. In FIG. 1D, lightemitters 152 mounted on mounting plate 166 are placed to face diffuser154 so that light emitted from light emitters 152 are directed to a faceof diffuser 154. Diffuser 154 includes a pattern 162 (e.g., an array ofa grid as shown in FIG. 1D), through which light is transmitted (withdiffusion). Diffuser 154 also includes portion 164 that blockstransmission of light. Thus, light from light emitters 152 passesthrough the pattern 162 and has the shape of the pattern 162.

Compared to second light source 150 shown in FIG. 1D, second lightsources 150 shown in FIGS. 1E-1G can have less thickness, which allowsplacement of lens assembly 110 closer to eye 170. The thickness ofsecond light source 150 (and more importantly, the ability to place lensassembly 110 closer to eye 170) is important. The size of a center holein diffuser 154 needs to be sufficiently small to project light fromsecond light source 150 on a central part of cornea 172. However, if thesize of the center hole in diffuser 154 is too small, only a small angleof light will be captured by lens assembly 110, which will reduce thereliability of wavefront sensing. Thus, one solution is to place lensassembly 110 as close toward eye 170, which allows lens assembly 110 tocapture more light without actually changing the diameter of the centerhole. In addition, placing lens assembly 110 closer toward eye 170(e.g., as a first optical element to receive light from eye 170) allowscapturing more light from eye 170, compared to placing a lens assemblyafter other optical elements (e.g., after beam steerer 122 or beamsteerer 126).

FIG. 1E illustrates a front view (shown on the left-hand side of FIG.1E) and a side view (shown on the right-hand side of FIG. 1E) of secondlight source 150 in accordance with some embodiments. In FIG. 1E, lightemitters 152 are placed around diffuser 154 so that light from lightemitters 152 is not sent directly to the face of diffuser 154. Instead,second light source 150 shown in FIG. 1E includes one or more mirrors(e.g., a conical mirror), which reflect light from second light source150 toward the face of diffuser 154. Light from second light source 150after passing through diffuser 154 has the shape of the pattern 162.

FIG. 1F illustrates a front view (shown on the left-hand side of FIG.1F), a side view (shown in the middle of FIG. 1F), and a cross-sectionalview (shown on the right-hand side of FIG. 1F) of second light source150 in accordance with some embodiments. In FIG. 1F, second light source150 includes light emitters 152 and diffuser 190. Diffuser 190 includesportion 192 that is transparent (e.g., optically transparent) to lightfrom light emitters 152 and portion 194 that is configured to diffuselight from light emitters 152. Light emitters 152 are placed along aperiphery of diffuser 190 so that light emitted from light emitters 152are transferred toward the periphery of diffuser 190.

FIG. 1G is similar to FIG. 1F, except that light emitters 152 arearranged on round mounting plate 166 instead of square mounting plate166.

Although diffusers 154 and 190 are each illustrated as a singlecomponent, in some embodiments, a diffuser includes multiple components(or multiple layers). For example, in some embodiments, a diffuserincludes a diffusion layer configured to diffuse, spread out, or scatterlight, and a separate masking layer for transmitting light in aparticular pattern. The diffusion layer can be made from ground glassand/or light scattering material, such as photopolymer and/orpolytetrafluoroethylene.

Turning back to FIG. 1A, second image sensor 160 is configured toreceive light, from eye 170, transmitted through lens assembly 110. Insome embodiments, the light from eye 170 includes light reflected fromcornea 172 of eye 170 (in response to the second light from second lightsource 150). For example, as shown in FIG. 1C, light from eye 170 (e.g.,light reflected from cornea 172) passes multiple optical elements, suchas lens assembly 110, beam steerer 122, lens 124, beam steerer 126, andlenses 156 and 158, and reaches second image sensor 160.

The lenses in the corneal topographer (e.g., lens assembly 110 andlenses 124, 156, and 158) are configured to image a pattern of lightprojected on cornea 172 onto second image sensor 160. For example, whenan array of spots is projected on cornea 172, the image of the array ofspots detected by second image sensor 160 is used to determine thetopography of cornea 172 (e.g., a profile of a surface of cornea 172 ora curvature of cornea 172).

FIG. 1H illustrates device 100 in accordance with some embodiments. InFIG. 1H, device 100 includes eyecup 196. In some embodiments, eyecup 196is configured to position the eye relative to the device. For example,eyecup 196 is configured to be placed against an orbit of the eye sothat the eye is positioned for optical measurements, such as wavefrontsensing and/or corneal topography measurements. Alternatively, in someembodiments, eyecup 196 is configured to block ambient light (e.g., withor without mechanically positioning the eye relative to device 100.

FIG. 2 is a block diagram illustrating electronic components of device100 in accordance with some embodiments. Device 100 typically includesone or more processing units 202 (central processing units, applicationprocessing units, application-specific integrated circuit, etc., whichare also called herein processors), one or more network or othercommunications interfaces 204, memory 206, and one or more communicationbuses 208 for interconnecting these components. In some embodiments,communication buses 208 include circuitry (sometimes called a chipset)that interconnects and controls communications between systemcomponents. In some embodiments, device 100 includes a user interface(e.g., a user interface having a display device, which can be used fordisplaying acquired images, one or more buttons, and/or other inputdevices). In some embodiments, device 100 also includes peripheralscontroller 252, which is configured to control operations of otherelectrical components of device 100, such as first light source 120,first image sensor 140, second light source 150, and second image sensor160 (e.g., initiating respective light sources to emit light, and/orreceiving information, such as images, from respective image sensors).

In some embodiments, communications interfaces 204 include wiredcommunications interfaces and/or wireless communications interfaces(e.g., Wi-Fi, Bluetooth, etc.).

Memory 206 of device 100 includes high-speed random access memory, suchas DRAM, SRAM, DDR RAM or other random access solid state memorydevices; and may include non-volatile memory, such as one or moremagnetic disk storage devices, optical disk storage devices, flashmemory devices, or other non-volatile solid state storage devices.Memory 206 may optionally include one or more storage devices remotelylocated from the processors 202. Memory 206, or alternately thenon-volatile memory device(s) within memory 206, comprises a computerreadable storage medium (which includes a non-transitory computerreadable storage medium and/or a transitory computer readable storagemedium). In some embodiments, memory 206 includes a removable storagedevice (e.g., Secure Digital memory card, Universal Serial Bus memorydevice, etc.). In some embodiments, memory 206 or the computer readablestorage medium of memory 206 stores the following programs, modules anddata structures, or a subset thereof:

-   -   operating system 210 that includes procedures for handling        various basic system services and for performing hardware        dependent tasks;    -   network communication module (or instructions) 212 that is used        for connecting device 100 to other computers (e.g., clients 302        and/or servers 304 shown in FIG. 3) via one or more        communications interfaces 204 and one or more communications        networks 306 (FIG. 3), such as the Internet, other wide area        networks, local area networks, metropolitan area networks, and        so on;    -   optical measurements application 214 that controls operations of        the light sources and the image sensors; and    -   security module 246 that protects data stored on device 100        during its storage on device 100 and/or transmission to and from        another computer (e.g., clients 302 and/or servers 304); for        example, security module 246 may include an encryption module        for encrypting data stored on device 100, a decryption module        for decrypting encrypted data, either stored on device 100 or        received from another computer, and an authentication module for        authenticating a user of device 100 and/or a remote computer for        communication with device 100 (e.g., for sending and/or        receiving data).

In some embodiments, memory 206 also includes one or both of:

-   -   user information 248 (e.g., information necessary for        authenticating a user of device 100); and    -   patient information 250 (e.g., optical measurement results        and/or information that can identify patients whose optical        measurement results are stored on device 100).

In some embodiments, optical measurements application 214 includes thefollowing programs, modules and data structures, or a subset or supersetthereof:

-   -   wavefront sensing module 216 configured for operating the        wavefront sensor in device 100;    -   corneal topography module 226 configured for operating the        corneal topographer in device 100;    -   image acquisition module 236 configured for analyzing images        collected by respective image sensors of device 100;    -   user input module 242 configured for handling user inputs on        device 100 (e.g., pressing of buttons of device 100, etc.); and    -   database module 244 configured to assist storage of data on        device 100 and retrieval of data from device 100 (in some        embodiments, database module 244 operates in conjunction with        security module 246).

In some embodiments, wavefront sensing module 216 includes the followingprograms and modules, or a subset or superset thereof:

-   -   first light source module 218 configured for initiating first        light source 120 (through peripherals controller 252) to emit        light;    -   first image sensing module 220 configured for receiving images        from first image sensor 140;    -   first analysis module 222 configured for analyzing images        received from first image sensor 140; and    -   first presentation module 224 configured for presenting        measurement and analysis results from first analysis module 222        (e.g., graphically displaying images received from first image        sensor 140, presenting aberrations shown in images received from        first image sensor 140, sending the results to another computer,        etc.).

In some embodiments, corneal topography module 226 includes thefollowing programs and modules, or a subset or superset thereof:

-   -   second light source module 228 configured for initiating second        light source 150 (through peripherals controller 252) to emit        light;    -   second image sensing module 230 configured for receiving images        from second image sensor 160;    -   second analysis module 232 configured for analyzing images        received from second image sensor 160; and    -   second presentation module 234 configured for presenting        measurement and analysis results from second analysis module 232        (e.g., graphically displaying images received from second image        sensor 160, presenting cornea curvatures determined from images        received from second image sensor 160, sending the results to        another computer, etc.).

In some embodiments, image acquisition module 236 includes the followingprograms and modules, or a subset or superset thereof:

-   -   image stabilization module 238 configured for reducing blurring        during acquisition of images by image sensors; and    -   spot array analysis module 240 configured for analyzing spot        arrays (e.g., measuring displacements and/or disappearances of        spots in the spot arrays).

In some embodiments, first image sensing module 220 initiates executionof image stabilization module 238 to reduce blurring during acquisitionof images by first image sensor 140, and second image sensing module 230initiates execution of image stabilization module 238 to reduce blurringduring acquisition of images by second image sensor 160.

In some embodiments, first analysis module 222 initiates execution ofspot array analysis module 240 to analyze spot arrays in images acquiredby first image sensor 140, and second analysis module 232 initiatesexecution of spot array analysis module 240 to analyze spot arrays inimages acquired by second image sensor 160.

Each of the above identified modules and applications correspond to aset of instructions for performing one or more functions describedabove. These modules (i.e., sets of instructions) need not beimplemented as separate software programs, procedures or modules, andthus various subsets of these modules may be combined or otherwisere-arranged in various embodiments. In some embodiments, memory 206 maystore a subset of the modules and data structures identified above.Furthermore, memory 206 may store additional modules and data structuresnot described above.

FIG. 3 is a block diagram illustrating a distributed computing system inaccordance with some embodiments. In FIG. 3, the distributed computingsystem includes one or more client computers 302, one or more serversystems 304, communications network 306, and device 100.

Client computers 302 can be any of a number of computing devices (e.g.,Internet kiosk, personal digital assistant, cell phone, smart phone,gaming device, desktop computer, laptop computer, handheld computer, orcombinations thereof) used to enable the activities described below.Client computer(s) 302 is also referred to herein as client(s). Client302 typically includes a graphical user interface (GUI). In someembodiments, client 302 is connected to device 100 via communicationsnetwork 106. As described in more detail below, the graphical userinterface is used to display results from device 100 (e.g., acquiredimages and/or analysis results). In some embodiments, one or moreclients are used to perform the analysis (for example, when device 100does not include sufficient computational capabilities, images can besent to one or more clients for analysis).

In some embodiments, the distributed computing system includes one ormore server systems (also called server computers) 304 connected tocommunications network 306. One or more server systems 304 store resultsfrom device 100 (and a plurality of similar devices). For example, oneor more server systems 304 store images transmitted from device 100and/or analysis results. In some embodiments, one or more server systems304 provide the stored images and/or analysis results to one or moreclients (e.g., computers used by medical professionals) 302. In someembodiments, one or more server systems 304 are used to perform theanalysis (e.g., the one or more servers analyze images sent by device100).

In some embodiments, communications networks 306 are the Internet. Inother embodiments, the communications networks 306 can be any local areanetwork (LAN), wide area network (WAN), metropolitan area network, or acombination of such networks. In some embodiments, communicationsnetworks 306 include a wired network and/or a wireless network (e.g.,Wi-Fi, Bluetooth, etc.).

In some embodiments, device 100 receives one or more softwareapplications or one or more software modules from one or more serversystems 304 or one or more clients 302 (e.g., using the wiredcommunication network and/or the wireless communication network).

Notwithstanding the discrete blocks in FIGS. 2 and 3, these figures areintended to be a functional description of some embodiments, although,in some embodiments, the discrete blocks in FIGS. 2 and 3 can be astructural description of functional elements in the embodiments. One ofordinary skill in the art will recognize that an actual implementationmight have the functional elements grouped or split among variouscomponents. In practice, and as recognized by those of ordinary skill inthe art, items shown separately could be combined and some items couldbe separated. For example, in some embodiments, security module 246 ispart of optical measurements application 214. In other embodiments,wavefront sensing module 216 and corneal topography module 226 areimplemented as separate applications.

FIG. 4 is a flowchart representing method 400 for optical measurements(e.g., wavefront sensing and keratometry (or corneal topography)) with aportable device, in accordance with some embodiments.

In some embodiments, method 400 includes (402) placing an orbit of theeye against an eyecup (e.g., eyecup 196 in FIG. 1H) associated with thelens assembly. In some embodiments, the eyecup blocks ambient light,which helps the pupil of the eye to dilate for more accurate wavefrontsensing.

Method 400 includes (404) transferring first light emitted from a firstlight source toward the eye through a lens assembly, and, in response totransferring the first light emitted from the first light source towardthe eye through a lens assembly, (406) transferring light from the eyethrough the lens assembly and an array of lenses; and receiving thelight from the eye, transferred through the lens assembly and the arrayof lenses, at a first image sensor. For example, as shown in FIG. 1B,first light emitted from first light source 120 is transferred towardeye 170 through lens assembly 110. In response, light from eye 170(e.g., light scattered and/or reflected from inside eye 170) istransferred through lens assembly 110 and the array of lenses 132, andis received at first image sensor 140.

In some embodiments, receiving the light from the eye at the first imagesensor includes acquiring multiple images of the light from the eye withthe first image sensor (e.g., multiple images are taken in a fewseconds, or even in less than a second).

Method 400 also includes (408) transferring second light emitted from asecond light source toward the eye, and, in response to transferring thesecond light emitted from the second light source toward the eye, (410)transferring light from the eye through the lens assembly; and receivingthe light from the eye, transferred through the lens assembly, at asecond image sensor. For example, as shown in FIG. 1C, second lightemitted from second light source 150 is transferred toward eye 170. Inresponse, light from eye 170 (e.g., light scattered and/or reflectedfrom cornea 172 of eye 170) is transferred through lens assembly 110,and received at second image sensor 160. In some embodiments, receivingthe light from the eye at the second image sensor includes acquiringmultiple images of the light from the eye with the second image sensor.

Method 400 further includes (412) analyzing the light received at thefirst image sensor and determining one or more aberrations associatedwith the eye. For example, displacements and/or disappearances of spotsin the image received at first image sensor 140 are measured and used todetermine one or more aberrations associated with eye 170.

Method 400 includes (414) providing information that indicates the oneor more aberrations associated with the eye. For example, a sphericalaberration and an astigmatism of the eye (e.g., in diopter) can bereported.

Method 400 includes (416) analyzing the light received at the secondimage sensor and determining a curvature of a cornea of the eye; and(418) providing information that indicates the curvature of the corneaof the eye. In some embodiments, method 400 includes determining acorneal topography of the eye (e.g., determining a profile of the corneaof the eye). In some embodiments, method 400 includes determining thecurvature of the cornea of the eye from the corneal topography of theeye. In some embodiments, method 400 includes determining two curvaturesof the cornea (e.g., flat radius and steep radius) and providinginformation that indicates both curvatures of the cornea. In someembodiments, method 400 includes providing information that indicates adifference between the two curvatures and an angle of a respectiveradius with respect to a reference axis of the eye (e.g., a horizontalaxis or a vertical axis). In some embodiments, method 400 includesproviding information that indicates an average of the two curvatures.

In some embodiments, the light received at the first image sensor has(420) a pattern of a first array of spots; and the light received at thesecond image sensor has a pattern of a second array of spots. Forexample, the light received at first image sensor 140 has a pattern ofan array of spots, because of the array of lenses 132 (e.g., each lensin the array of lenses 132 is responsible for a single spot on firstimage sensor 140). The light received at second image sensor 160generally has a pattern of light projected on cornea 172 of eye 170(e.g., FIG. 7). Unlike conventional corneal topographers, which utilizea pattern of concentric rings, a pattern of an array of spots can beprojected on cornea 172 of eye 170, and the light received at secondimage sensor 160 also has a pattern of an array of spots. The use of anarray of spots enables images acquired by second image sensor 160 to beanalyzed in a similar manner as images acquired by first image sensor140. In addition, it has been found that the use of a pattern of anarray of spots for corneal topography further improves an accuracy ofthe corneal topography. Because an array of spots provides more discretepoints to track, compared to conventional concentric rings, theresolution of corneal topography can be further improved with the use ofa pattern of an array of spots.

In some embodiments, analyzing the light received at the first imagesensor and analyzing the light received at the second image sensor bothinclude (422): determining a centroid of the light received at arespective image sensor; and determining a deviation of each spot oflight received at the respective image sensor. Thus, deviations (ordisplacements) of the spots are used to determine aberrations (in caseof wavefront sensing) and/or deformations of the cornea (in case ofcorneal topography).

It should be understood that the particular order in which theoperations in FIG. 4 have been described is merely exemplary and is notintended to indicate that the described order is the only order in whichthe operations could be performed. One of ordinary skill in the artwould recognize various ways to reorder the operations described herein.For example, the analyzing operation (412) may be performed before thetransferring operation (408). In another example, the analyzingoperation (416) may be performed in conjunction with the analyzingoperation (412), before the providing operation (414). Additionally, itshould be noted that details of other processes described herein withrespect to method 500 described herein are also applicable in ananalogous manner to method 400 described above with respect to FIG. 4.For example, the transferring, receiving, and analyzing operations,described above with reference to method 400 optionally have one or moreof the characteristics of the transferring, receiving, and analyzingoperations described herein with reference to method 500 describedherein. For brevity, these details are not repeated here.

FIG. 5 is a flowchart representing method 500 of optical measurements(e.g., wavefront sensing and keratometry (or corneal topography)) with aportable device, in accordance with some embodiments.

Method 500 is performed at an electronic device (e.g., device 100) thatincludes one or more processors (e.g., processors 202, FIG. 2) andmemory (e.g., memory 206, FIG. 2) storing instructions for execution bythe one or more processors.

Method 500 includes (502) initiating a first light source to emit firstlight (e.g., using first light source module 218 to initiate first lightsource 120 to emit first light). The first light emitted from the firstlight source is transferred toward an eye through a lens assembly. Forexample, as shown in FIG. 1B, the first light emitted from first lightsource 120 is transferred toward eye 170 through lens assembly 110.

Method 500 includes, while the first light source emits the first light,(504) receiving, at a first image sensor, a first image of light fromthe eye, transferred through the lens assembly and an array of lenses(e.g., using first image sensing module 220).

Method 500 includes (506) initiating a second light source to emitsecond light (e.g., using second light source module 228 to initiatesecond light source 150 to emit second light). The light emitted fromthe second light source is transferred toward the eye. For example, asshown in FIG. 1C, the second light emitted from second light source 10is transferred toward eye 170.

Method 500 includes (508), while the second light source emits thesecond light, receiving, at a second image sensor, a second image oflight from the eye, transferred through the lens assembly (e.g., usingsecond image sensing module 230).

In some embodiments, method 500 includes, in conjunction with receivingthe second image of the light from the eye, (510) collecting an image ofthe eye with the second image sensor. For example, an image of the eyeis acquired with second image sensor 160. This image can be used todetermine whether the eye is properly positioned for opticalmeasurements (e.g., wavefront sensing and/or corneal topography). Insome embodiments, the image of the eye is collected with the secondimage sensor in temporal proximity to receiving the second image of thelight from the eye. This reduces any error due to the movement of theeye between collecting the image of the eye and receiving the secondimage. For example, the image of the eye is collected with the secondimage sensor immediately before receiving the second image of the lightfrom the eye. Alternatively, the image of the eye is collected with thesecond image sensor immediately after receiving the second image of thelight from the eye. In some embodiments, method 500 includes providingthe image of the eye for display to a user and receiving a user input(e.g., pressing on a “go” or “acquire” button) to initiate receiving thesecond image.

In some embodiments, method 500 includes (512) confirming whether alocation of the eye satisfies predefined alignment criteria. Forexample, method 500 includes determining that the eye is offset from thecenter of the image by more than a distance, and in response, providinga warning (e.g., either a visible or audible warning to indicate thatthe second image may not be usable or the result may not be accurate)and/or preventing receiving of the second image.

In some embodiments, method 500 includes (514) determining a position ofthe eye from the image of the eye collected with the second imagesensor; and adjusting one or more aberrations associated with the eyebased on the position of the eye determined from the image of the eyecollected with the second image sensor. The inventors of thisapplication have found that the measurement of the power of the eye isincorrect if the eye is placed away from a pupil plane of device 100.The inventors of this application have also discovered that the errorcan be corrected if the distance from the eye to the pupil plane ofdevice 100 is known. FIG. 6 illustrates exemplary calibration curvesthat can be used to calibrate the measurements. For example, if the eyeis positioned away from the pupil plane of device 100 by 12 mm, themeasured power of the eye may be off by approximately 10%. Thus, themeasured power of the eye should be adjusted accordingly.

In some embodiments, method 500 includes (516) determining a size of apupil of the eye from the image of the eye collected with the secondimage sensor. This allows a user of device 100 to ensure that the pupilsize is sufficient to measure high order aberrations, because high orderaberrations are difficult to measure if the pupil size is notsufficiently large.

In some embodiments, method 500 includes: (518) analyzing the firstimage and determining one or more aberrations associated with the eye(e.g., determining spherical aberrations and astigmatism of the eye);and analyzing the second image and determining a curvature of a corneaof the eye. In some embodiments, determining the curvature of the corneaof the eye includes determining a corneal topography of the eye.

In some embodiments, the instructions include a predefined set ofinstructions for analyzing an image that includes an array of spots(e.g., spot array analysis module 240 in FIG. 2). Analyzing the firstimage and determining the one or more aberrations associated with theeye include (520) executing the predefined set of instructions foranalyzing an image that includes an array of spots; and analyzing thesecond image and determining the curvature of the cornea of the eye alsoinclude executing the predefined set of instructions for analyzing animage that includes an array of spots. Because the same predefined setof instructions is used for analyzing both images received at the firstimage sensor and at the second image sensor, the software applicationcan be made smaller, faster, and more efficient.

It should be understood that the particular order in which theoperations in FIG. 5 have been described is merely exemplary and is notintended to indicate that the described order is the only order in whichthe operations could be performed. One of ordinary skill in the artwould recognize various ways to reorder the operations described herein.Additionally, it should be noted that details of other processesdescribed herein with respect to method 400 described herein are alsoapplicable in an analogous manner to method 500 described above withrespect to FIG. 5. For example, the transferring, receiving, andanalyzing operations, described above with reference to method 500optionally have one or more of the characteristics of the transferring,receiving, and analyzing operations described herein with reference tomethod 400 described herein. For brevity, these details are not repeatedhere.

FIG. 6 illustrates exemplary calibration curves for adjusting one ormore aberrations of an eye based on a position of the eye relative tothe device, in accordance with some embodiments. In FIG. 6, each curverepresents measured spherical powers of simulated eyes (e.g., simulatedby representative lenses of known powers) as functions of their true(nominal) spherical powers. The curves shown in FIG. 6 also indicatethat the measured spherical powers of the simulated eyes vary dependingon the position of the eye. As explained above, if the eye is positionedaway from the pupil plane of device 100 by 12 mm, the measured power ofthe eye can be off by as much as 10%. By using the calibration curvesshown in FIG. 6, the true spherical power of an eye can be determined.Furthermore, the error caused by the position of the eye can be reduced.

FIG. 7 is an exemplary image of an eye with projection of a spot arraypattern in accordance with some embodiments. As shown in FIG. 7, thesport array pattern has a shape of a grid, unlike concentric circlesused in conventional Placido corneal topographers. As described above,the use of the spot array pattern improves the accuracy of cornealtopography, and also improves the processing of images for cornealtopography by portable devices, because the same set of instructions canbe used for analyzing both images for wavefront sensing and images forcorneal topography. The details of using the spot array pattern, whichare described above, are not repeated here.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the scope of claims to the precise forms disclosed. Manymodifications and variations are possible in view of the aboveteachings. The embodiments were chosen and described in order to bestexplain the principles of the various described embodiments and theirpractical applications, to thereby enable others skilled in the art tobest utilize the invention and the various described embodiments withvarious modifications as are suited to the particular use contemplated.

What is claimed is:
 1. A method performed by a portable devicecomprising a lens assembly, a wavefront sensor, and a keratometer, themethod comprising: transferring first light emitted from a first lightsource toward an eye through the lens assembly; in response totransferring the first light emitted from the first light source towardthe eye through a lens assembly: transferring light from the eye throughthe lens assembly and an array of lenses; and receiving the light fromthe eye, transferred through the lens assembly and the array of lenses,at a first image sensor; transferring second light emitted from a secondlight source toward the eye; in response to transferring the secondlight emitted from the second light source toward the eye: transferringlight from the eye through the lens assembly; and receiving the lightfrom the eye, transferred through the lens assembly, at a second imagesensor; analyzing the light received at the first image sensor anddetermining one or more aberrations associated with the eye; providinginformation that indicates the one or more aberrations associated withthe eye; analyzing the light received at the second image sensor anddetermining a curvature of a cornea of the eye; and providinginformation that indicates the curvature of the cornea of the eye,wherein: the light received at the first image sensor has a pattern of afirst array of spots; the light received at the second image sensor hasa pattern of a second array of spots; analyzing the light received atthe first image sensor and analyzing the light received at the secondimage sensor both include: determining a centroid of the light receivedat a respective image sensor; and determining a deviation of each spotof light received at the respective image sensor.
 2. The method of claim1, including: placing an orbit of the eye against an eyecup associatedwith the lens assembly.
 3. The method of claim 1, wherein: the wavefrontsensor includes: the lens assembly; the first light source configured toemit first light and transfer the first light emitted from the firstlight source toward the eye through the lens assembly; the array oflenses that is distinct from the lens assembly; and the first imagesensor configured to receive light, from the eye, transmitted throughthe lens assembly and the array of lenses; and the keratometer includes:the lens assembly; the second light source that is distinct from thefirst light source and configured to emit second light and transfer thesecond light emitted from the second light source toward the eye; andthe second image sensor configured to receive light, from the eye,transmitted through the lens assembly.
 4. The method of claim 3, whereinthe second light source is configured to transfer the second lightemitted from the second light source toward the eye without transmittingthe second light emitted from the second light source through the lensassembly.
 5. The method of claim 3, wherein the second light source isconfigured to project an array of spots on the eye.
 6. The method ofclaim 3, wherein the second light source includes a diffuser with a spotarray pattern and one or more light emitters placed behind the diffuserand configured to emit light toward the diffuser.
 7. The method of claim3, wherein the second light source includes a diffuser with a spot arraypattern and one or more light emitters and one or more reflectorsarranged to send light toward the diffuser from behind the diffuser. 8.The method of claim 3, wherein the second light source includes adiffuser with a spot array pattern and a plurality of light emittersplaced along a periphery of the diffuser, wherein at least a firstportion of the diffuser is transparent and at least a second portion ofthe diffuser is configured to diffuse light.
 9. The method of claim 3,wherein the lens assembly includes a lens that is tilted from an opticalaxis of the device.
 10. The method of claim 3, wherein the first lightsource is configured to transfer the first light emitted from the firstlight source off an optical axis of the device.
 11. The method of claim3, wherein the first image sensor is configured to receive the lightfrom the eye while the first light source emits the first light.
 12. Themethod of claim 3, wherein the second image sensor is configured toreceive the light from the eye while the second light source emits thesecond light.
 13. The method of claim 3, wherein the lens assembly is adoublet lens.
 14. The method of claim 3, wherein the lens assemblyincludes two or more separate lenses.
 15. The method of claim 3, whereinthe device includes: a beam steerer configured to transfer light fromthe eye, transmitted through the lens assembly, toward the first imagesensor and/or the second image sensor.
 16. The method of claim 15,wherein the beam steerer is a beam splitter.
 17. The method of claim 3,wherein the device includes: an eyecup configured to position the eyerelative to the device.
 18. A portable device, comprising: a wavefrontsensor that includes: a first light source configured to emit firstlight and transfer the first light emitted from the first light sourcetoward an eye through the lens assembly; an array of lenses; and a firstimage sensor configured to receive light, from the eye, transmittedthrough the lens assembly and the array of lenses, wherein the lightreceived at the first image sensor has a pattern of a first array ofspots; and a keratometer that includes: a second light source that isdistinct from the first light source and configured to emit second lightand transfer the second light emitted from the second light sourcetoward the eye, wherein the second light source is configured to projectan array of spots on the eye; and a second image sensor configured toreceive light, from the eye, transmitted through the lens assembly,wherein the light received at the second image sensor has a pattern of asecond array of spots, wherein the portable device is configured to:analyze the light received at the first image sensor and analyze thelight received at the second image sensor, both including: determining acentroid of the light received at a respective image sensor; anddetermining a deviation of each spot of light received at the respectiveimage sensor.